CAVS to MTS Converter

Convert CAVS to MTS: What This Tutorial Covers

This converter takes a raw Chinese AVS (AVS1) video stream and wraps it into an MTS (AVCHD) file so you can drop Chinese-broadcast archive footage into a camcorder-style editing timeline. One thing to know up front: a bare .cavs is video only, so the MTS it produces will be a real, playable video that is silent — no soundtrack, because there was none inside the source. This tutorial explains why, walks through the quality settings, and points most users to a better target.

How to Convert CAVS to MTS

1. Upload Your CAVS File: Drag and drop your .cavs onto the page, or click "+ Add Files" to choose it from your computer. You can queue several clips to run with the same settings.
2. Pick a Quality Preset: Open "Show All Options" and leave Quality Preset on its default (Very High (Recommended)), or switch File Compression to Constant Bitrate, Variable Bitrate, Constant Quality, or Constraint Quality to set the rate yourself. AVCHD is an H.264 format, so the MTS encodes to H.264 by default.
3. Set Resolution or Trim (Optional): Video resolution defaults to Keep original; use Preset Resolutions or Width × Height to rescale, or use Time Range under Trim to export just part of the timeline. A standard-definition broadcast source stays SD — rescaling up will not add real detail.
4. Convert and Download: Click "Convert" and download your .mts file. No sign-up, no watermark.

Walk-through: Why the Picture Survives but the Sound Doesn't

A bare .cavs is the video half of a recording: a sequence of coded AVS1 frames with no container, no index, and no parallel audio track. MTS wrapping keeps that video intact, so the moving footage transfers fine — what it cannot transfer is audio that was never in the file. AVS1 defines video coding only; the video coding part was promulgated as China's national standard GB/T 20090.2 in February 2006, with efficiency competitive with the H.264 of its era. Any sound that accompanied the footage was encoded separately and carried in the container the video was demuxed from. A few practical patterns:

• You only need the footage to edit, not the audio — the default settings are fine; the silent MTS drops straight into an AVCHD timeline, and you add a separate audio track there.
• You want the smallest file — switch File Compression to Constant Quality or a lower Variable Bitrate; the H.264 pass re-encodes the AVS1 video to your chosen rate.
• You need only part of a long clip — set a Time Range under Trim instead of exporting the whole timeline.
• You expected sound — the settings above change nothing about the silence; you need a different source file, covered below.

Common Errors and How to Fix Them

• "My MTS plays but has no sound" — Expected when the input is a true raw .cavs. AVS1 is a video elementary stream with no audio inside, so there is nothing to mux into the MTS. Convert the container the video came from instead — TS to MTS or MP4 to MTS.
• "My player shows zero length or won't open the .cavs" — A bare elementary stream has no container header or index, so most players refuse it directly; tools built on FFmpeg read it through a dedicated raw AVS demuxer, and some VLC builds with AVS decoding can play it. This is normal for a stripped stream, not corruption.
• "The MTS looks softer than the original" — AVS1 to H.264 is a lossy-to-lossy re-encode, so the H.264 pass cannot recover detail the AVS compression already discarded. Raise the bitrate or use Constant Quality to minimize the loss; you cannot regain quality the source never kept.
• "The file is binary garbage in a text editor" — Good: that means it is genuine coded AVS video, not an AviSynth .avs script. If it does open as readable text, see the FAQ below — it is a different kind of file entirely.

When This Doesn't Work

If your goal was a clip with sound, no MTS setting can create audio that is not in the source — the data simply is not there. Chinese AVS broadcast and optical-media content is almost always muxed into an MPEG transport stream (.ts) or an .mp4 that wraps the AVS video next to a separate audio track; when that container was demuxed down to a bare .cavs, the audio was left behind in the original. Go back to that .ts or .mp4 and convert it, and the audio rides along. And if you do not specifically need the AVCHD container — most people do not — CAVS to MP4 gives you the same H.264 video in a far more widely supported file that today's players and devices open directly.

Frequently Asked Questions

Why does my CAVS to MTS file have no sound?

Because a bare .cavs is a Chinese AVS (AVS1) video elementary stream and carries no audio at all. AVS1 defines video coding only, so there is no soundtrack packed inside a raw .cavs for the tool to mux into the MTS. The MTS itself is a complete, playable AVCHD video — it just plays silently because the source had no audio stream. That sound lived in the container the video was demuxed from, usually an MPEG transport stream (.ts) or an .mp4. To keep it, convert that container instead: TS to MTS or MP4 to MTS.

The clip played with sound earlier — where did the audio go?

It is still in the original container, not in the .cavs. Chinese AVS broadcast and optical-media content is muxed: the AVS video and a separate audio track are packed together inside an MPEG transport stream or MP4. When a tool demuxes that file down to a bare .cavs, it keeps only the video elementary stream and leaves the audio behind in the source. Point the converter at the original .ts or .mp4 (TS to MTS, MP4 to MTS) and the audio track is read and muxed into the MTS normally.

Will converting AVS to AVCHD improve the quality?

No. AVCHD uses H.264 and your .cavs is already AVS1, so this is a lossy-to-lossy re-encode: the H.264 pass cannot recover detail the AVS1 compression already discarded, and a fresh lossy encode is slightly softer than the source. A standard-definition broadcast .cavs (typically 720×480 or 720×576) also stays standard-definition — wrapping it as MTS does not make it HD. The point of this conversion is workflow compatibility, getting the footage into an AVCHD-style editor, not a quality gain.

Should I convert CAVS to MTS, or to MP4?

For most people, MP4 is the better target. MTS/AVCHD makes sense only when a specific camcorder-oriented editor or device expects .mts files; if you simply want a clip that plays widely and edits easily, CAVS to MP4 gives you the same H.264 video in a friendlier, far more universally supported container. Both will be silent if the source is a true video-only .cavs, so the missing-audio caveat above applies either way.

Could my file actually be an AviSynth .avs script instead?

Worth checking, because the extensions look similar. An .avs AviSynth file is a small text script that tells a video frameserver how to process other clips — it is not video data and not Chinese AVS, and it holds no audio or video to convert at all. A .cavs (Chinese AVS) file is genuine coded video, developed under China's AVS Workgroup, which was founded in June 2002. If your file opens as readable text in an editor, it is an AviSynth script. If it is binary coded data from Chinese digital TV or broadcast, it is a real AVS1 video stream — still video-only, so the silent-output explanation above applies.

How are my files handled, and are they kept private?

Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion — never shared or made public. There is no sign-up and no watermark. In our testing, a genuine raw .cavs video stream converts to a clean, playable MTS that is silent every time, while feeding a real .ts or .mp4 container that holds an audio track produces an MTS with sound.